Challenging Pitfalls and Mimickers in Diagnosing Anastomosing Capillary Hemangioma of the Kidney: Case Report and Literature Review

Abstract

BACKGROUND Vascular tumors of the kidney are rare tumors that are usually diagnosed and confirmed by histopathological examination due to the difficulty in definitive diagnosis by clinical and radiological examination. Anastomosing hemangioma is a rare variant of capillary hemangioma that mimics angiosarcoma. CASE REPORT Here, we present a case of a 55-year-old female with a history of partial nephrectomy due to clear cell renal cell carcinoma three years earlier, who presented with a contralateral anastomosing capillary hemangioma. The diagnosis was confirmed by histopathology and immunohistochemistry studies. CONCLUSIONS Anastomosing hemangioma is a rare variant of capillary hemangioma. It has a sinusoidal growth pattern which resembles splenic parenchyma. It mimics malignant neoplasms, thus, clinical and radiological examination are not enough for accurate diagnosis. In this paper, we discuss the most crucial differential diagnoses and the pitfalls in diagnosing this rare variant of hemangioma. Furthermore, we present a literature review of all cases reported in the English-language literature.

Figure 1.

Enhanced CT scan shows left renal hypodense solid mass with areas of cystic degeneration and peripherally enhanced thick solid component.

Figure 2.

Histopathology of renal anastomosing hemangioma (H&E). (A) Low power micrograph (2×) histological examination showed a well-demarcated but un-encapsulated mass with small renal tubules entrapped at the periphery of the lesion. (B) Tumor cells are composed of sinusoidal anastomosing capillaries, similar to the red pulp of spleen (40×). (C) High power view demonstrate endothelial cells lining blood vessels are simple cuboidal in shape no significant cellular atypia are seen (H&E, 400×). (D) Stromal changes show sclerosis and deposition of collagen between the sinusoidal vascular channels (40×).

Figure 3.

(A) Vascular channels of tumor cells with extravasated red blood cells. (B) Sclerotic stroma with vascular fibrin thrombi deposition (A and B, H&E) (HE, 20×) (C) Immunohistochemistry: tumor cells showed diffuse strong positive for CD31 (4×). (D) Immunohistochemistry: intravascular stromal cells showed strongly positive for factor VIII (4×).

Figure 4.

A bar chart demonstrating the reported cases of anastomosing hemangioma in the kidney correlating gender, age at presentation and mean size of the lesion.

Figure 5.

An error bar demonstrating the relationship between gender, age at presentation, and mean size of the lesion of the reported cases of anastomosing hemangioma.